Swivel joints are commonly used in the oilfield industry to build rigid yet dynamically configurable flow lines between various pieces of equipment. For example, in oilfield pumping stimulation operations, or fracking operations, swivel joints are often used to connect a number of high pressure pumping units to a manifold and to connect the manifold to an injection wellhead.
These types of swivel joints typically comprise a tubular male member which is rotatably connected to a tubular female member. The male member comprises a male race and the female member comprises a female race which is configured to be receive the male race. When the male race is positioned in the female race, each of a plurality of outer annular grooves on the male race is aligned with a corresponding inner annular groove on the female race to thereby form plurality of bearing races within which a plurality of balls are received to rotatably connect the male member to the female member.
When the male and female members are connected together, an annulus is formed between the male and female races which is in fluid communication with the flow bore defined by the swivel joint. In order to contain the fracking fluid within the flow bore while still allowing the male and female members to rotate relative to each other, the swivel joint usually includes a dynamic primary seal which is positioned between a nose portion of the male race and an inner end portion of the female race.
However, if the primary seal fails, the flow of pressurized fracking fluid through the annulus can quickly erode the male nose portion and/or the female inner end portion and thereby cause the swivel joint to fail. Also, pressurized fluid will enter the annulus and generate hydrostatic end loads between the male and female races which could cause the bearing races to fail.